21152728 has 8 divisors (see below), whose sum is σ = 39661380. Its totient is φ = 10576360.

The previous prime is 21152713. The next prime is 21152731. The reversal of 21152728 is 82725112.

It is a tau number, because it is divible by the number of its divisors (8).

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21152696 and 21152705.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1322038 + ... + 1322053.

Almost surely, 2^21152728 is an apocalyptic number.

It is an amenable number.

21152728 is a deficient number, since it is larger than the sum of its proper divisors (18508652).

21152728 is a wasteful number, since it uses less digits than its factorization.

21152728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2644097 (or 2644093 counting only the distinct ones).

The product of its digits is 2240, while the sum is 28.

The square root of 21152728 is about 4599.2094972941. The cubic root of 21152728 is about 276.5596360243.

The spelling of 21152728 in words is "twenty-one million, one hundred fifty-two thousand, seven hundred twenty-eight".